Wireless Router making main Computer Slow?

I just installed a Linksys Cisco Wireless N router to my iMac I bought last February and it has turned my internet connection extremely slow. the iMac is the Main PC and is actually hooked up to the Linksys via the blue ethernet cord. I noticed a delay when opening a new page and when trying to open links and or images. Do I need a faster, or better router? We bought the router so we can hook up a PS3 and Wii wirelessly to the internet, but now my PC internet is so much slower. I have a cable modem that worked so fast before! What should I do?